Half power supply voltage generating circuit for a semiconductor device

Abstract

A half power supply voltage generating circuit receiving first and second power supply voltages and comprising; a bias circuit for generating first and second reference voltages in response to the first and second power supply voltages, and a driver circuit receiving the first and second reference voltages and generating a half power supply voltage, the driver circuit comprising four MOS transistors connected in series between the first and second supply voltages.

What is claimed is: 
     
       1. A half power supply voltage generating circuit receiving first and second power supply voltages and comprising: a bias circuit receiving said first and second power supply voltages and generating first and second reference voltages in response to said first and second power supply voltages; and   a driver circuit receiving said first and second power supply voltages and said first and second reference voltages, and generating a half power supply voltage at a half power supply voltage node, said driver circuit comprising; a first MOS transistor of first conductivity type having a first source connected to said first power supply voltage, a first gate connected to said half power supply voltage node, and a first drain;   a second MOS transistor of second conductivity type having a second source connected to said half power supply voltage node, a second gate connected to said first reference voltage, and a second drain connected to said first drain;   a third MOS transistor of first conductivity type having a third source connected to said half power supply voltage node, a third gate connected to said second reference voltage, and a third drain; and   a fourth MOS transistor of second conductivity type having a fourth source connected to said second power supply voltage, a fourth gate connected to said half power supply voltage node, and a fourth drain connected to said third drain.     
     
     
       2. The half power supply voltage generating circuit of claim 1, wherein said second power supply voltage has a ground potential. 
     
     
       3. The half power supply voltage generating circuit of claim 1, wherein said first conductivity type is p-type and said second conductivity type is n-type. 
     
     
       4. The half power supply voltage generating circuit of claim 1, wherein said bias circuit comprises: a fifth MOS transistor of first conductivity type having a fifth source connected to said first power supply voltage, a fifth gate connected to said second power supply voltage, and a fifth drain connected to a first voltage node;   a sixth MOS transistor of second conductivity type having a sixth source connected to a third voltage node, a sixth gate and a sixth drain connected to said first voltage node at which said first reference voltage is apparent;   a seventh MOS transistor of first conductivity type having a seventh source connected to said third voltage node, a seventh gate and a seventh drain connected to a second voltage node at which said second reference voltage is apparent; and   an eighth MOS transistor of second conductivity type having an eighth source connected to said second power supply voltage, an eighth gate connected to said first power supply voltage, and an eighth drain connected to said second voltage node.   
     
     
       5. The half power supply voltage generating circuit of claim 4, wherein said first conductivity type is p-type and said second conductivity type is n-type. 
     
     
       6. The half power supply voltage generating circuit of claim 4, wherein said second power supply voltage has a ground potential. 
     
     
       7. The half power supply voltage generating circuit of claim 1, wherein said bias circuit comprises: a fifth MOS transistor of first conductivity type having a fifth source connected to said first power supply voltage, a fifth gate connected to said half power supply voltage node, and a fifth drain connected to a first voltage node;   a sixth MOS transistor of second conductivity type having a sixth source connected to a third voltage node, a sixth gate and a sixth drain connected to said first voltage node at which said first reference voltage is apparent;   a seventh MOS transistor of first conductivity type having a seventh source connected to said third voltage node, a seventh gate and a seventh drain connected to a second voltage node at which said second reference voltage is apparent; and   an eighth MOS transistor of second conductivity type having an eighth source connected to said second power supply voltage, an eighth gate connected to said half power supply voltage node, and an eighth drain connected to said second voltage node.   
     
     
       8. The half power supply voltage generating circuit of claim 7, wherein said first conductivity type is p-type and said second conductivity type is n-type. 
     
     
       9. The half power supply voltage generating circuit of claim 7, wherein said second power supply voltage has a ground potential.